Reproduction steps:
1. Create a new project (any template supporting “HDR Display Output” is fine)
2. Go to Edit > Project Settings…
3. In the Project Settings window, search for a setting to adjust Editor interface HDR Paper White value/Editor UI brightness (use the Search box)

Expected result: A setting that changes the Editor’s UI Paper White value exists and allows for Editor’s interface brightness adjustment
Actual result: No such setting exists, Editor UI Paper White nits are locked (seemingly at 160.0f nits)

Reproducible with: 2021.3.52f1, 2022.3.62f1, 6000.0.50f1, 6000.1.4f1, 6000.2.0b3

Reproduced on: Windows 11 Pro (24H2)
Not reproduced on: No other environment tested

Notes:
- The current approach of how the Editor’s interface handles HDR Display Output is lacking because of this issue, therefore, this is reported as a Usability issue instead of a Feature Request
- It is impossible to adjust the brightness of the Editor’s interface independently from the Scene/Game view
- For certain users, the Editor’s interface may look uncomfortably bright and for others, uncomfortably dark, even though the interface itself is locked at the same brightness value because each display and system process HDR signals differently; hence, a setting to adjust Editor’s interface brightness in HDR is indeed a necessity